A dozen juveniles from Minnesota are among the 251 victims in what is being described as one of the largest online child exploitation investigations in the history of the U.S. Immigration and Customs Enforcement (ICE).

Victims who were sexually exploited on Internet websites were identified in five countries and 39 states, including North Dakota, South Dakota and Iowa.

A 33-year-old Minneapolis man, Sean Jabbar, has been charged with receiving child pornography as part of the wide-ranging federal inquiry.

In many cases, the children were enticed to perform sexual acts on common Internet webcam services such as Skype, authorities said.

The operators are accused of running a digital child exploitation enterprise that routinely preyed on young boys, producing and distributing pornographic videos of minors and coaching others on strategies to coerce underage boys into participating in sexual acts. They are accused of tapping into social networking sites and sometimes impersonating females online to initiate conversation.

Jabbar is among 14 men arrested and indicted as part of a conspiracy to operate a child exploitation enterprise through a child porn website on the Darknet’s Onion Router, also known as Tor.

Shawn Neudauer, a local ICE spokesman, said Jabbar, who was indicted on receipt of child pornography, was arrested at his residence in Minneapolis late last year. An indictment against him says he received the materials from September 2012 to April 2013.

If convicted, Jabbar could face a mandatory minimum sentence of five years and a maximum sentence of 20 years in prison.

Neudauer said the 12 Minnesota victims came from all parts of the state. In addition, there were 12 victims from North Dakota, two from South Dakota, and six from Iowa.

While the investigation is continuing, Neudauer said there is no evidence to suggest any of the victims actually met the perpetrators.

The final results of the investigation, which included arrests over several months, were announced Tuesday.

The website’s primary administrator, Jonathan Johnson, 27, of Abita Springs, La., has been charged with operating the enterprise. He admitted to creating multiple fake female personas on popular social networks to target and sexually exploit children. Johnson has been in federal custody since his arrest June 13, 2013, and faces 20 years to life in prison.

Authorities said the underground website was a hidden service board on the Tor network and operated from about June 2012 until June 2013. At that time, ICE said in a release, the site contained more than 2,000 videos and had more than 27,000 members. The website shared webcam-captured videos of mostly juvenile boys enticed by the operators of the site to produce sexually explicit material. Tor enables online anonymity, directing Internet traffic through a volunteer network consisting of thousands of relays to conceal a user’s location.

The investigation was dubbed “Operation Round Table” and began with Johnson’s arrest. Eleven men have been federally charged in the Eastern District of Louisiana and three in other districts. All are in federal custody.

Federal authorities suggest parents should be wary of the Internet usage of their children, particularly if they play online games such as World of Warcraft, which can involve thousands of anonymous players. They also suggest parents should warn children about revealing too much information online, including passwords, home addresses or school locations.

The National Center for Missing and Exploited Children has set up a program called NetSmartzkids that provides age-appropriate resources to help teach children how to be safer on- and offline.